<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
    <style type="text/css">
     .lv {
        color: red;
      }
    </style>
  </head>
  <body>
    <div>绿叶学习网</div>
    <div class="lv">绿叶学习网</div>
    <div class="lv">绿叶学习网</div>
  </body>
</html>